update json-schema generation with new package structure.

[pchainho]

Update json-schema generation tool according to new package structure as discussed in #16

json-schema generation tool should be moved to this repo: src/tools

[shumy]

I'm trying to figure out what should be the new output. For example, picking the message.cduml and one of the genereted files Message.json:

{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "id": "Message",
    "type": "object",
    "required": ["id", "from", "type", "contextId", "body", "messageType", "uRL", "messageBodyArray"],
    "additionalProperties": false,
    "properties": {
        "id": {
            "type": "string"
        },
        "from": {
            "$ref": "../URL/URL.json"
        },
        "to": {
            "$ref": "../URL/URLList.json"
        },
        "type": {
            "$ref": "../Message/MessageType.json"
        },
        "contextId": {
            "type": "null"
        },
        "body": {
            "$ref": "../Message/MessageBody.json"
        },
        "signature": {
            "type": "null"
        }
        ,
        "messageType": {
            "$ref": "../Message/MessageType.json"
        },
        "uRL": {
            "$ref": "../URL/URL.json"
        },
        "messageBodyArray": {
            "$ref": "../Message/MessageBody.json"
        }
    }
}

How should I generate the references? I was trying to use the concept of "definitions" http://spacetelescope.github.io/understanding-json-schema/structuring.html But this requires to define a top level class in the package. This can work in message.cduml if considering the top level class of the same name of the package, but it's not always possible.

[shumy]

Another problem that as came up is related to mismatch between UML definitions and JSON Schema. This is not a technical problem and there's nothing wrong with the actual generated schemas, it's just, they are not as useful as it seems. The way JSON Schema is validated, is starting on a root object and verifies every field and reference attached to it. However class diagrams don't strictly follow a tree structure. Even if we define a root object, if there are detached definitions (with inverted references), these are not validated. JSON schema is directly related to document databases. But class diagramas define better, relational databases. I don't see a way to solve this, unless carefully designing the class diagrams. By following a tree structure and by separating in different packages. Any ideas are wellcome.

[shumy]

Found other minor issues:

1. How to define some special types. Currently URL's are defined as classes, these are converted to JSON object definitions. However URL's are formatted strings instead.
2. When defining a reference in PlantUML like ClassX --> ClassY there is no place to define the reference variable name. The placeolder after the definition could be used like ClassX --> ClassY:name but this is currently defined as free text (not suitable to a variable name, because it can have spaces).
3. There are some circular references in the model and can be a problem when validating data, creating infinite loops.
4. There are no arrays or references to native types.

Some proposed solutions:

1. Use the PlantUML feature "specific spot" to define custom type elements. Just add <<(T,orchid)>> to the class definition to be a Type definition.
2. Use the relation description for variable name, and drop the general purpose.
3. Do not generate inverted references. For example ClassX --> ClassY will be the same as ClassX -- ClassY assuming the left to right direction. But I would rather prefer that UML be corrected instead.
4. Should be defined as "field: type[]"

[pchainho]

1. Use the PlantUML feature "specific spot" to define custom type elements. Just add <<(T,orchid)>> to the class definition to be a Type definition.

ok

1. Use the relation description for variable name, and drop the general purpose.

We agreed to ignore associations like ClassX --> ClassY and to just take into account attributs defined in each class.

1. Do not generate inverted references. For example ClassX --> ClassY will be the same as ClassX -- ClassY assuming the left to right direction.

This one should not be an issue anymore since we agreed to ignore plantuml associations

1. Should be defined as "field: type[]"

ok

[shumy]

Parser was not prepared to accept relations beetween packages. It's was updated, but no JSON is generated for this.

[shumy]

Parser was updated, and schemas generated.

1. Code and tool available at "tools/plantuml-json-parser/"
2. Model sources available at "schemas/"
3. JSON Schemas available at "schemas/json-schema/"

[pchainho]

Not done according to previously agreed structure

[pchainho]

partially done according to agreed structure. It is ready to be used for the validation of data synch objects.